Many industries presently make use of rotating drums for treating various materials. For example, at a coal fired steam generating plant, the ash discharged from a furnace is often treated in a rotating drum. One problem encountered in such an installation is forming an effective seal around the stationary inlet duct for the rotating drum. Existing seals for this application frequently leak after a short period of operation due to wear or the inability of the seal to follow the rotating surface. If the material being treated is at a high temperature, as ash may be, it can add to the problem by causing warpage or uneven thermal expansion of the various pieces of equipment. Leakage of hot, abrasive material, such as ash, into the atmosphere, can cause damage to the other machine parts and also is environmentally hazardous.